Williams, Hoshide Outside to Complete MBSU Installation

Flight Engineers Suni Williams and Aki Hoshide began their second spacewalk in less than a week at 7:06 a.m. EDT today. They are working to complete the installation of a Main Bus Switching Unit (MBSU) that was hampered last week by a possible misalignment and damaged bolt threads.

Williams and Hoshide built some improvised tools to assist with their installation tasks. The tools will be used to clean the bolts and receptacles and repair the bolt threads.

MBSU cleaning tools to be used for installation work during the spacewalk. Credit: NASA TV

If the astronauts are unable to install the MBSU, an option exists to return it to the airlock for further analysis and troubleshooting.

Flight Engineer Joe Acaba is the Canadarm2 operator and will monitor the spacewalkers from inside the International Space Station. Hoshide will ride the Canadarm2 attached to a portable foot restraint to the MBSU worksite.

Today’s spacewalk is scheduled to last 6.5 hours and includes other tasks postponed from last week’s excursion if the MBSU installation task is completed on time.

Last week’s spacewalk lasted eight hours and 17 minutes making it the third longest in U.S. spaceflight history. It was originally scheduled for 6.5 hours before mission controllers and the astronauts struggled to install the MBSU.

Today’s spacewalk is the third for Expedition 32. Commander Gennady Padalka and Flight Engineer Yuri Malenchenko completed a five-hour, 51-minute excursion on Aug. 20. They worked to move a Strela-2 cargo boom which allows the Pirs docking compartment to be undocked at a later date.